Just Plug It In: Networking Via Power Circuits
HomePlug makes it easy to use existing in-wall wiring for fast home networks.
Yardena Arar - From the April 2002 issue of PC World magazine

No new wires. That's the mantra of almost everyone contemplating a home or small-office network, which is why wireless networks have become so popular. But a new standard that uses existing electrical wiring, HomePlug, could offer users a real alternative to wireless.

We tried out the first HomePlug networking products and found them easy to install, robust, and fast. They're especially suitable for hooking up desktop systems in larger homes and in small offices where wireless options may not be practical because of signal attenuation (related to distance from an access point).

HomePlug isn't the first technology to use existing wiring: The HomePNA standard for networks using telephone circuits was first published more than three years ago, and other power-line products have launched in the past. But previous power-line efforts were hampered by a combination of poor performance and a lack of standards, and HomePNA networks using telephone wires are hampered by the relative scarcity of telephone jacks in most homes. HomePlug, which lets you network devices by plugging an external adapter into a standard wall outlet, delivers performance superior to that of 802.11b wireless networks at only a small price premium--no more than $25 to $50 per computer.

For our tests, we tried out three paperback book-size, preproduction Linksys Instant Powerline products: two EtherFast 10/100 Bridges and one USB adapter (each at a street price of $149).

Making Connections
To network two PCs, we hooked one of the EtherFast 10/100 Bridges to the first system's standard ethernet port, and the USB adapter to the second PC's USB port. To add Internet access, we plugged the second EtherFast 10/100 Bridge into a conventional network router, which in turn was connected to a broadband modem (see diagram). Alternatively, if you have static IP addresses for your computers, you can substitute a hub for a router. By the time you read this, Linksys expects to release a $179 router with HomePlug technology built in, eliminating a box. Other vendors that expect to ship HomePlug components in the next few months include GigaFast, Netgear, Phonex Broadband, and SMC Networks.

We tested the adapters in a single-family home and in a condominium in a 29-unit building, using them to transfer files and surf the Web. The network ran flawlessly everywhere we plugged in, except for one outlet in the single-family home (HomePlug engineers say wiring quirks will occasionally cause this, but typically a nearby outlet will work just fine).

In these informal tests, the network appeared largely unaffected by our use of power strips and household electrical appliances, a problem that had plagued previous power-line networking systems. However, audiophiles who use special power conditioners to "clean up" electrical signals could run into problems if they plug a HomePlug unit into the conditioner, as the filtering system might perceive the network traffic as noise and filter it out.

The HomePlug specification protects your data from the prying eyes of others on your power grid by using DES encryption--as opposed to the RC4 algorithm, whose implementation in 802.11b has known security flaws--that works at the MAC address level (the unique identifier for each piece of hardware). Officials at Intellon, the chip maker that developed the HomePlug spec, say that hacking into a HomePlug network would require cracking the government's DES encryption standard.

Faster Than 802.11b
HomePlug's theoretical maximum speed of 14 megabits per second is slightly faster than 802.11b's 11-mbps top speed, as well as the 10-mbps speed of older ethernet networks. Because typical broadband Internet access tops out at 1.5 mbps, neither network type gives you an advantage for Web surfing. But we were surprised at how much faster HomePlug was than 802.11b for file transfers. Transferring an 11MB file between our two HomePlug-equipped notebooks took only about 30 seconds, compared with 1 minute, 15 seconds when we substituted 802.11b PC Cards. Intellon engineers say this probably happened because HomePlug allowed data to flow directly between the two side-by-side notebooks (even with the router installed), while the 802.11b traffic had to move via the more distant router and back.

Additionally, HomePlug is not subject to other wireless traffic or to interference from walls and doors, all of which can significantly slow down 802.11b signals, especially if larger distances are involved.

Drawbacks? HomePlug is not supercheap--you can purchase 802.11b USB adapters for slightly less. It's also not ideal for notebooks, especially if you're often on the move: No HomePlug PC Cards have been announced, and having the paperback-size adapter as well as a standard AC adapter hanging off the back of your notebook is definitely cumbersome. In fact, people who wish to network both notebooks and desktop systems should consider creating their own hybrid 802.11b/HomePlug network, built around an 802.11b router with at least one extra ethernet port. Plug a HomePlug ethernet bridge into the router, slip an 802.11b PC Card into the notebook, plug your desktops into the wall outlet, and you have the best of both worlds.